Fair Value of Assets and Liabilities - Schedule of Changes in Level 3 Fair Value Assets and Liabilities on a Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Liabilities
Beginning balance, Total	$ 37,135	$ 112,293	$ 65,837	$ 178,755
Purchases of Borrower Loans/Issuance of Notes	874,913	641,915	2,344,401	1,837,430
Principal repayments	(4,087)	(22,377)	(29,266)	(82,649)
Borrower Loans sold to third parties	(903,418)	(642,474)	(2,373,390)	(1,838,015)
Other changes	(297)	(176)	(688)	(885)
Change in fair value	(931)	(2,673)	(3,579)	(8,128)
Ending balance, Total	3,315	86,508	3,315	86,508
Prosper Funding LLC
Liabilities
Beginning balance, Total	1,696	2,677	1,437	2,548
Purchases of Borrower Loans/Issuance of Notes	874,913	641,915	2,344,401	1,837,430
Principal repayments	215	806	1,490	1,194
Borrower Loans sold to third parties	(875,088)	(642,474)	(2,345,060)	(1,838,015)
Borrower Loans contributed by Parent, at fair value	1,581		1,581
Other changes	161	57	168	38
Change in fair value	(163)	(620)	(702)	(834)
Ending balance, Total	3,315	2,361	3,315	2,361
Notes
Liabilities
Beginning balance, Liabilities	(221,070)	(264,001)	(243,900)	(283,030)
Purchases of Borrower Loans/Issuance of Notes	(35,178)	(42,318)	(107,162)	(126,900)
Principal repayments	38,694	46,563	122,317	141,344
Borrower Loans sold to third parties	0	0	0	0
Other changes	68	140	476	477
Change in fair value	5,090	4,078	15,873	12,571
Ending balance, Liabilities	(212,396)	(255,538)	(212,396)	(255,538)
Notes \| Prosper Funding LLC
Liabilities
Beginning balance, Liabilities	(221,070)	(264,001)	(243,900)	(283,030)
Purchases of Borrower Loans/Issuance of Notes	(35,178)	(42,318)	(107,162)	(126,900)
Principal repayments	38,694	46,563	122,317	141,344
Borrower Loans sold to third parties	0	0	0	0
Borrower Loans contributed by Parent, at fair value	0		0
Other changes	69	140	477	477
Change in fair value	5,089	4,078	15,872	12,571
Ending balance, Liabilities	(212,396)	(255,538)	(212,396)	(255,538)
Borrower Loans
Assets
Beginning balance, Assets	258,205	376,294	309,737	461,785
Purchases of Borrower Loans/Issuance of Notes	35,795	42,332	109,434	128,165
Principal repayments	(42,781)	(68,940)	(151,583)	(223,993)
Borrower Loans sold to third parties	(29,122)	(573)	(31,261)	(1,850)
Other changes	(365)	(316)	(1,164)	(1,362)
Change in fair value	(6,021)	(6,751)	(19,452)	(20,699)
Ending balance, Assets	215,711	342,046	215,711	342,046
Borrower Loans \| Prosper Funding LLC
Assets
Beginning balance, Assets	222,766	266,678	245,337	285,578
Purchases of Borrower Loans/Issuance of Notes	35,795	42,332	109,434	128,165
Principal repayments	(38,479)	(45,757)	(120,827)	(140,150)
Borrower Loans sold to third parties	(792)	(573)	(2,931)	(1,850)
Transfer of Credit Card interest receivables upon close of PMCC 2026-1	1,581		1,581
Other changes	92	(83)	(309)	(439)
Change in fair value	(5,252)	(4,698)	(16,574)	(13,405)
Ending balance, Assets	215,711	257,899	215,711	257,899
Loans Held For Sale
Assets
Beginning balance, Assets	0	0	0	0
Purchases of Borrower Loans/Issuance of Notes	874,296	641,901	2,342,129	1,836,165
Principal repayments	0		0	0
Borrower Loans sold to third parties	(874,296)	(641,901)	(2,342,129)	(1,836,165)
Other changes	0	0	0	0
Change in fair value	0	0	0	0
Ending balance, Assets	0	0	0	0
Loans Held For Sale \| Prosper Funding LLC
Assets
Beginning balance, Assets	0	0	0	0
Purchases of Borrower Loans/Issuance of Notes	874,296	641,901	2,342,129	1,836,165
Principal repayments	0	0	0	0
Borrower Loans sold to third parties	(874,296)	(641,901)	(2,342,129)	(1,836,165)
Transfer of Credit Card interest receivables upon close of PMCC 2026-1	0		0
Other changes	0	0	0	0
Change in fair value	0	0	0	0
Ending balance, Assets	$ 0	$ 0	$ 0	$ 0

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